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Individual study: An evaluation of mitigation actions for great crested newts at development sites

Published source details

Lewis B. (2012) An evaluation of mitigation actions for great crested newts at development sites. PhD thesis. The Durrell Institute of Conservation and Ecology, University of Kent.


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Legal protection of species Amphibian Conservation

A review from 2000 to 2010 of great crested newt Triturus cristatus mitigation licences issued in England and Wales, UK (Lewis 2012) found that the number issued had increased. Licences issued in England increased from 273 in 2000 to over 600 in 2009. In Wales numbers increased from seven in 2001 to 26 in 2010. Of the licences examined, only 41% of English licences and 30% Welsh licences contained reporting (‘return’) documents, a condition of the licence. Reporting had therefore decreased since 1990–2001 (45%; Edgar, Griffiths & Foster 2005). Of those that reported, only 9% provided post-development monitoring data, a further 7% suggested surveys were undertaken but no data were provided. The majority of English (71%) and Welsh (56%) licences were for small populations (<10 recorded). Just over half of projects were considered to be of ‘low impact’, a quarter ‘medium impact’ and 20% ‘high impact’ to newts. A review of the governmental licensing authorities (Natural England and Welsh Assembly Government) licence files was undertaken.

 

Create artificial hibernacula or aestivation sites Amphibian Conservation

A continuation of a study (Lewis, Griffiths & Barrios 2007) in 2005–2010 of four mitigation projects in England, UK (Lewis 2012) found that providing artificial hibernacula and refugia, along with other management for great crested newts Triturus cristatus helped to maintain populations. Numbers initially decreased at two sites (2005: over 100 to 19; 42 to 31), but increased to 60 newts at both sites by 2009 and 2010 respectively. Populations decreased from 2005 to 2010 at the other two sites (167 to 10; 86 to 40). Artificial hibernacula and refugia were created at sites in 1992–1999. Terrestrial habitat management was also undertaken at the sites and one site received 73 translocated newts. Monitoring was undertaken in March–May using egg searches, torch surveys, bottle trapping and mark-recapture.

Legal protection of species Amphibian Conservation

In a continuation of a study (Lewis 2012), a systematic review in 2011 of the effectiveness of mitigation actions for legally protected great crested newts Triturus cristatus in the UK (Lewis 2012) found that neither the 11 studies captured or monitoring data from licensed mitigation projects showed conclusive evidence that mitigation resulted in self-sustaining populations or connectivity to populations in the wider countryside. Only 5% of 460 licensed projects provided post-development monitoring data and of those, 16 reported that small populations, three medium and one large population was sustained. Two reported a loss of populations. The review identified 11 published or unpublished studies and 309 Natural England and 151 Welsh Assembly Government (licensing authorities) mitigation licence files. Mitigation measures were undertaken to reduce the impact of the development and included habitat management, as well as actions to reduce mortality including translocations.

 

Create ponds for great crested newts Amphibian Conservation

A before-and-after study in 1998–2011 of eight created ponds in unimproved grassland in Kent, UK (Lewis 2012) found that great crested newts Triturus cristatus established a population in the ponds. The population increased by 30% within the first year following construction. The population was 10–14 newts in 2000–2006, increased to 32 in 2008 following draining and relining of ponds and then to 40 following construction of four additional ponds. Larvae were recorded in six ponds. There was no significant preference for older or newer ponds (117 vs 134 captures), apart from the first-time breeders that tended to colonize new ponds more than old ponds. Four experimental ponds (2 x 1 m; maximum depth 0.7 m) were created in a row in 1998 and four in 2009. Populations were sampled weekly in March–May using bottle trapping, torch surveys and mark-recapture.

 

Create ponds for great crested newts Amphibian Conservation

A systematic review in 2011 of the effectiveness of mitigation actions for great crested newts Triturus cristatus in the UK (Lewis 2012) found that neither the 11 studies captured or monitoring data from licensed mitigation projects showed conclusive evidence that mitigation, which often included pond creation, resulted in self-sustaining populations or connectivity to populations in the wider countryside. Only 22 of 460 licensed projects provided post-development monitoring data and of those, 16 reported that small populations, three medium and one large population was sustained. Two reported a loss of the population. A total of 127 (41%) of English and 46 (30%) of Welsh licence files contained licence return (reporting) documents. Of those, only 9% provided post-development monitoring data, a further 7% suggested surveys were undertaken, but no data were provided. The review identified 11 published or unpublished studies and 309 Natural England and 151 Welsh Assembly Government (licensing authorities) mitigation licence files. Mitigation measures were undertaken to reduce the impact of the development and included habitat management such as creating or restoring ponds, as well as actions to reduce deaths including translocations.

 

Translocate great crested newts Amphibian Conservation

A systematic review in 2011 of the effectiveness of mitigation actions for great crested newts Triturus cristatus in the UK (Lewis 2012) found that none of the 11 studies captured nor monitoring data from licensed mitigation projects showed conclusive evidence to suggest that mitigation that included translocations resulted in self-sustaining populations or connectivity to populations in the wider countryside. Only 22 of 460 licensed projects provided post-development monitoring data and of those, 16 reported that small, three medium and one large population was sustained. Two reported a loss of the population. The review identified 11 published or unpublished studies together with 309 Natural England and 151 Welsh Assembly Government (licensing authorities) mitigation licence files. Mitigation measures were undertaken to reduce the impact of development and included habitat management such as creating or restoring ponds, as well as actions to reduce deaths including translocations.

 

 

Clear vegetation Amphibian Conservation

A continuation of a study (Lewis, Griffiths & Barrios 2007) in 2006–2010 of a mitigation site in England, UK (Lewis 2012) found that although vegetation clearance, along with other terrestrial and aquatic habitat management, initially maintained a great crested newt Triturus cristatus population, numbers then declined. The number of newts recorded declined from 167 in 2005, six years after management, to just 10 in 2010. Management included tree felling, clearance of both terrestrial and aquatic vegetation and the re-profiling of ponds. Artificial hibernacula and refugia were also created in 1999. Monitoring was undertaken in March–May using egg searches, torch surveys and bottle trapping.

 

Restore ponds Amphibian Conservation

A systematic review in 2011 of the effectiveness of mitigation actions for great crested newts Triturus cristatus in the UK (Lewis 2012) found that neither the 11 studies found or monitoring data from licensed mitigation projects showed conclusive evidence that mitigation, which often included pond restoration, resulted in self-sustaining populations or connectivity to populations in the wider countryside. Only 22 of 460 licensed projects provided post-development monitoring data and of those, 16 reported that small, three medium and one large population was sustained. Two reported a loss of the population. A total of 127 (41%) of English and 46 (30%) of Welsh licence files contained licence return (reporting) documents. Of those, only 9% provided post-development monitoring data and a further 7% suggested surveys were undertaken, but no data were provided. The review identified 11 published or unpublished studies together with 309 Natural England and 151 Welsh Assembly Government (licensing authorities) mitigation licence files. Mitigation measures were undertaken to reduce the impact of the development and included habitat management such as creating or restoring ponds, as well as actions to reduce deaths including translocations.